Scope of the Intramolecular Titanocene-Catalyzed Pauson−Khand Type Reaction<sup>1</sup>
作者:Frederick A. Hicks、Natasha M. Kablaoui、Stephen L. Buchwald
DOI:10.1021/ja990682u
日期:1999.6.1
A Pauson−Khandtype conversion of enynes to bicycliccyclopentenones employing the commercially available precatalyst titanocene dicarbonyl is described. This methodology shows excellent functional group tolerance for a group 4 metallocene-catalyzed process. The scope and limitations of this cyclization with respect to 1,6-, 1,7- and 1,8-enynes with a variety of terminal alkyne substituents, chiral
The synthesis of azabicycloalkenones bearing a vinylogous amide moiety was achieved by means of the rhodium-catalyzed decarbonylative cycloaddition of cyclobutenediones with a pendant alkene. The starting cyclobutenediones were efficiently prepared from appropriate squaricacid monoesters and N-benzylalkenylamines under microwave heating conditions.
A method for synthesis of bicyclo[3.3.0]oct-1-en-3-ones from cyclobutanones with one-carbon ring expansion and its application to a formal synthesis of racemic 1-desoxyhypnophilin
method for synthesis of 2-cyanobicyclo[3.3.0]oct-1-en-3-ones and 2-substituted bicyclo[3.3.0]oct-1-en-3-ones was developed by assembly of three components, cyclobutanones, chloromethyl p-tolyl sulfoxide, and nitriles, with one-carbon ring expansion of the cyclobutane ring. As an application of this method, a formal synthesis of 1-desoxyhypnophilin in racemic form was performed starting from 3,3-di(p
substituent at the 3-position. Heating of the enaminonitriles with H3PO4 in acetic acid gave 2-substituted bicyclo[3.3.0]oct-1-en-3-ones in good to high yields. This method offers a novel and versatile procedure for synthesis of 2-substituted bicyclo[3.3.0]oct-1-en-3-ones from cyclobutanones in good overall yields.
由环丁酮和氯甲基对甲苯基亚砜合成的[氯(对甲苯甲硫基)亚甲基]环丁烷可分三步以高总收率进行处理,过量的氰基甲基锂则可以高产率得到烯腈。用乙酸中的H 3 PO 4加热这些烯腈,得到高产率的2-氰基双环[3.3.0] oct-1-en-3-one。另一方面,用氰基甲基锂处理[氯(对甲苯基亚磺酰基)亚甲基]环丁烷,然后将乙腈同系物的碳负离子锂化,得到在3-位具有取代基的烯氨基腈。用H 3 PO 4加热烯腈在乙酸中的乙酸得到高至高产率的2-取代的双环[3.3.0] oct-1-en-3-one。该方法提供了一种新颖且通用的方法,可从环丁酮以良好的总收率合成2-取代的双环[3.3.0] oct-1-en-3-ones。
The Catalytic Pauson-Khand Reaction Promoted by A Small Amount of 1,2-Dimethoxyethane or Water
作者:Takumichi Sugihara、Masahiko Yamaguchi
DOI:10.1055/s-1998-1991
日期:1998.12
Various "hard" Lewis bases having less nucleophilic nature promoted the catalytic Pauson-Khand reaction. Among those Lewis bases, 1,2-dimethoxyethane seems to be the most promising promoter and a small amount of water, which is the cheapest reagent, also effectively promoted the cyclization.